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<div class="titlepage"><div><div><h3 class="title">
<a name="boost_asio.reference.DynamicBuffer_v1"></a><a class="link" href="DynamicBuffer_v1.html" title="Dynamic buffer requirements (version 1)">Dynamic buffer
      requirements (version 1)</a>
</h3></div></div></div>
<p>
        A dynamic buffer encapsulates memory storage that may be automatically resized
        as required, where the memory is divided into an input sequence followed
        by an output sequence. These memory regions are internal to the dynamic buffer
        sequence, but direct access to the elements is provided to permit them to
        be efficiently used with I/O operations, such as the <code class="computeroutput"><span class="identifier">send</span></code>
        or <code class="computeroutput"><span class="identifier">receive</span></code> operations of
        a socket. Data written to the output sequence of a dynamic buffer sequence
        object is appended to the input sequence of the same object.
      </p>
<p>
        A dynamic buffer type <code class="computeroutput"><span class="identifier">X</span></code> shall
        satisfy the requirements of <code class="computeroutput"><span class="identifier">MoveConstructible</span></code>
        (C++ Std, [moveconstructible]) types in addition to those listed below.
      </p>
<p>
        In the table below, <code class="computeroutput"><span class="identifier">X</span></code> denotes
        a dynamic buffer class, <code class="computeroutput"><span class="identifier">x</span></code>
        denotes a value of type <code class="computeroutput"><span class="identifier">X</span><span class="special">&amp;</span></code>, <code class="computeroutput"><span class="identifier">x1</span></code>
        denotes values of type <code class="computeroutput"><span class="keyword">const</span> <span class="identifier">X</span><span class="special">&amp;</span></code>,
        and <code class="computeroutput"><span class="identifier">n</span></code> denotes a value of
        type <code class="computeroutput"><span class="identifier">size_t</span></code>, and <code class="computeroutput"><span class="identifier">u</span></code> denotes an identifier.
      </p>
<div class="table">
<a name="boost_asio.reference.DynamicBuffer_v1.t0"></a><p class="title"><b>Table 13. DynamicBuffer_v1 requirements</b></p>
<div class="table-contents"><table class="table" summary="DynamicBuffer_v1 requirements">
<colgroup>
<col>
<col>
<col>
</colgroup>
<thead><tr>
<th>
                <p>
                  expression
                </p>
              </th>
<th>
                <p>
                  type
                </p>
              </th>
<th>
                <p>
                  assertion/note<br> pre/post-conditions
                </p>
              </th>
</tr></thead>
<tbody>
<tr>
<td>
                <p>
                  <code class="computeroutput"><span class="identifier">X</span><span class="special">::</span><span class="identifier">const_buffers_type</span></code>
                </p>
              </td>
<td>
                <p>
                  type meeting <a class="link" href="ConstBufferSequence.html" title="Constant buffer sequence requirements">ConstBufferSequence</a>
                  requirements.
                </p>
              </td>
<td>
                <p>
                  This type represents the memory associated with the input sequence.
                </p>
              </td>
</tr>
<tr>
<td>
                <p>
                  <code class="computeroutput"><span class="identifier">X</span><span class="special">::</span><span class="identifier">mutable_buffers_type</span></code>
                </p>
              </td>
<td>
                <p>
                  type meeting <a class="link" href="MutableBufferSequence.html" title="Mutable buffer sequence requirements">MutableBufferSequence</a>
                  requirements.
                </p>
              </td>
<td>
                <p>
                  This type represents the memory associated with the output sequence.
                </p>
              </td>
</tr>
<tr>
<td>
                <p>
                  <code class="computeroutput"><span class="identifier">x1</span><span class="special">.</span><span class="identifier">size</span><span class="special">()</span></code>
                </p>
              </td>
<td>
                <p>
                  <code class="computeroutput"><span class="identifier">size_t</span></code>
                </p>
              </td>
<td>
                <p>
                  Returns the size, in bytes, of the input sequence.
                </p>
              </td>
</tr>
<tr>
<td>
                <p>
                  <code class="computeroutput"><span class="identifier">x1</span><span class="special">.</span><span class="identifier">max_size</span><span class="special">()</span></code>
                </p>
              </td>
<td>
                <p>
                  <code class="computeroutput"><span class="identifier">size_t</span></code>
                </p>
              </td>
<td>
                <p>
                  Returns the permitted maximum of the sum of the sizes of the input
                  sequence and output sequence.
                </p>
              </td>
</tr>
<tr>
<td>
                <p>
                  <code class="computeroutput"><span class="identifier">x1</span><span class="special">.</span><span class="identifier">capacity</span><span class="special">()</span></code>
                </p>
              </td>
<td>
                <p>
                  <code class="computeroutput"><span class="identifier">size_t</span></code>
                </p>
              </td>
<td>
                <p>
                  Returns the maximum sum of the sizes of the input sequence and
                  output sequence that the dynamic buffer can hold without requiring
                  reallocation.
                </p>
              </td>
</tr>
<tr>
<td>
                <p>
                  <code class="computeroutput"><span class="identifier">x1</span><span class="special">.</span><span class="identifier">data</span><span class="special">()</span></code>
                </p>
              </td>
<td>
                <p>
                  <code class="computeroutput"><span class="identifier">X</span><span class="special">::</span><span class="identifier">const_buffers_type</span></code>
                </p>
              </td>
<td>
                <p>
                  Returns a constant buffer sequence <code class="computeroutput"><span class="identifier">u</span></code>
                  that represents the memory associated with the input sequence,
                  and where <code class="computeroutput"><span class="identifier">buffer_size</span><span class="special">(</span><span class="identifier">u</span><span class="special">)</span> <span class="special">==</span> <span class="identifier">size</span><span class="special">()</span></code>.
                </p>
              </td>
</tr>
<tr>
<td>
                <p>
                  <code class="computeroutput"><span class="identifier">x</span><span class="special">.</span><span class="identifier">prepare</span><span class="special">(</span><span class="identifier">n</span><span class="special">)</span></code>
                </p>
              </td>
<td>
                <p>
                  <code class="computeroutput"><span class="identifier">X</span><span class="special">::</span><span class="identifier">mutable_buffers_type</span></code>
                </p>
              </td>
<td>
                <p>
                  Requires: <code class="computeroutput"><span class="identifier">size</span><span class="special">()</span> <span class="special">+</span> <span class="identifier">n</span> <span class="special">&lt;=</span>
                  <span class="identifier">max_size</span><span class="special">()</span></code>.<br>
                  <br> Returns a mutable buffer sequence <code class="computeroutput"><span class="identifier">u</span></code>
                  representing the output sequence, and where <code class="computeroutput"><span class="identifier">buffer_size</span><span class="special">(</span><span class="identifier">u</span><span class="special">)</span> <span class="special">==</span> <span class="identifier">n</span></code>. The dynamic buffer reallocates
                  memory as required. All constant or mutable buffer sequences previously
                  obtained using <code class="computeroutput"><span class="identifier">data</span><span class="special">()</span></code> or <code class="computeroutput"><span class="identifier">prepare</span><span class="special">()</span></code> are invalidated.<br> <br>
                  Throws: <code class="computeroutput"><span class="identifier">length_error</span></code>
                  if <code class="computeroutput"><span class="identifier">size</span><span class="special">()</span>
                  <span class="special">+</span> <span class="identifier">n</span>
                  <span class="special">&gt;</span> <span class="identifier">max_size</span><span class="special">()</span></code>.
                </p>
              </td>
</tr>
<tr>
<td>
                <p>
                  <code class="computeroutput"><span class="identifier">x</span><span class="special">.</span><span class="identifier">commit</span><span class="special">(</span><span class="identifier">n</span><span class="special">)</span></code>
                </p>
              </td>
<td>
              </td>
<td>
                <p>
                  Appends <code class="computeroutput"><span class="identifier">n</span></code> bytes
                  from the start of the output sequence to the end of the input sequence.
                  The remainder of the output sequence is discarded. If <code class="computeroutput"><span class="identifier">n</span></code> is greater than the size of
                  the output sequence, the entire output sequence is appended to
                  the input sequence. All constant or mutable buffer sequences previously
                  obtained using <code class="computeroutput"><span class="identifier">data</span><span class="special">()</span></code> or <code class="computeroutput"><span class="identifier">prepare</span><span class="special">()</span></code> are invalidated.
                </p>
              </td>
</tr>
<tr>
<td>
                <p>
                  <code class="computeroutput"><span class="identifier">x</span><span class="special">.</span><span class="identifier">consume</span><span class="special">(</span><span class="identifier">n</span><span class="special">)</span></code>
                </p>
              </td>
<td>
              </td>
<td>
                <p>
                  Removes <code class="computeroutput"><span class="identifier">n</span></code> bytes
                  from beginning of the input sequence. If <code class="computeroutput"><span class="identifier">n</span></code>
                  is greater than the size of the input sequence, the entire input
                  sequence is removed. All constant or mutable buffer sequences previously
                  obtained using <code class="computeroutput"><span class="identifier">data</span><span class="special">()</span></code> or <code class="computeroutput"><span class="identifier">prepare</span><span class="special">()</span></code> are invalidated.
                </p>
              </td>
</tr>
</tbody>
</table></div>
</div>
<br class="table-break">
</div>
<div class="copyright-footer">Copyright © 2003-2025 Christopher M.
      Kohlhoff<p>
        Distributed under the Boost Software License, Version 1.0. (See accompanying
        file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
      </p>
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